1. Field of the Invention
The present invention relates to a direct lighting type liquid crystal display device, and more particularly to a direct lighting type liquid crystal display device having a plurality of lamp units easily replaced by positioning flexible printed circuit (FPC) connecters electrically connecting a source printed circuit board to a control board among those lamp units.
2. Description of the Related Art
A cathode ray tube (CRT) is generally used as a display device, and applied to a television receiver, a measurement instrument, a monitor of an information display device and so on. The CRT, however, has a heavy weight and a large size so that the CRT may not applied for a display device having a small size and a light weight.
Hence, a liquid crystal display device having a thin thickness, low power consumption, and a light weight is developed for replacing the CRT. Recently, the liquid crystal display device has more developed to sufficiently display information on a larger screen so that the liquid crystal display device is utilized for monitors of a laptop computer, a desktop computer or any other display apparatuses having large screens. Thus, the demands for the liquid crystal display device is more increased.
The liquid crystal display device is a non-emissive display device which can display an image by controlling light inputted from outside. Thus, the liquid crystal display device should have a light source such as a back light assembly for applying light to a liquid crystal display panel thereof. The back light assemblies are divided into an edge type back light assembly and a direct lighting type back light assembly in accordance with positions of lamp units of the liquid crystal display device.
In the edge type back light assembly, the lamp units are installed on a side of light guiding plate which guides the light. The edge type back light assembly has lamps for emitting the light, lamp holders located end portions of the lamps for protecting the lamps, and a reflection sheet enclosing the lamps for reflecting the light emitted from the lamps into light guiding plate.
The edge type back light assembly can be applied to a liquid crystal display having small size such as the monitors of the laptop computer or the desktop computer. The edge type back light assembly has a uniform light distribution, a good durability and a thin thickness, thereby minimizing the thickness of the liquid crystal display device.
Meanwhile, the direct lighting type back light assembly is developed according as a liquid crystal display device has a screen having size of more than 20 inches. Light emitted from a plurality of lamps is directly illuminated onto a liquid crystal as display panel of a liquid crystal display device including the direct lighting type back light assembly having a diffusion plate.
The direct lighting type back light assembly has a light efficiency higher than that of the edge typed back light assembly so that the direct lighting type back light assembly can be utilized for a display apparatus having a large screen.
However, the lamps may have some troubles in comparison with the liquid crystal display device having the edge type back light assembly because many lamps are installed under the diffusion plate of the liquid crystal display device including the direct lighting type back light assembly. In the liquid crystal display device having the edge type back light assembly in which lamp units are installed on sides of the light guiding plate, only luminance of the screen is reduced when one lamp gets out of order. In the liquid crystal display device including the direct lighting type back light assembly, the image displayed on the screen is directly deteriorated when one lamp is out of order because the lamps are installed beneath the screen. As a result, the lamps of the direct lighting type back light assembly should be frequently replaced. However, time for replacing the lamp may be increased and workability for replacing the lamp may be reduced because the troubled lamp can be replaced with a new lamp after a top chassis is separated from a mold frame and a bottom chassis is also separated from the mold frame in order to replace the troubled lamp.
To overcome above-mentioned problem, there is provided a direct lighting type liquid crystal display device including at least two lamp units and slide slots at Korean Patent Application No. 1999-825. In the direct lighting type liquid crystal display device, the lamp units are separated each other and the slide slots are formed on side portions of a bottom chassis corresponding to the lamp units. The slide slots are closed with a cover. When a troubled lamp of the direct lighting liquid crystal display device is replaced, the lamp unit including the troubled lamp is drawn from the bottom chassis through the slide slots after the slide slots are separated from the bottom chassis, and then the troubled lamp is replaced with a new one. In the direct lighting type liquid crystal display device, two source printed circuit boards are installed at end portions of a liquid crystal display panel along a longitudinal direction concerning the liquid crystal display panel. First end portions of the FPC connecters are connected to the source printed circuit boards and second end portions of the FPC connecters are connected to the control board after the FPC connecters are bent toward a rear face of the bottom chassis where the control board is positioned along a side of the bottom chassis including the slide slots from the source printed circuit boards.
However, in the above-mentioned direct lighting liquid crystal display device, the workability for replacing the troubled lamp is still lowered because the FPC connecters, which electrically connect the source printed circuit boards installed in the liquid crystal display device to the control board disposed on an outside of the liquid crystal display device, and a protection plate for protecting the control board is separated from the control board so as to replace the troubled lamp with new lamp after a side cover is separated from the bottom chassis.
That is, the FPC connecters that are placed over an upper face of the side cover should be separated from the control board in order to separate the FPC connecters from the control board through the slide slots. Also, portions of signal lines of the FPC connecters may be broken at corners of a lower face of the bottom chassis where the signal lines are bent toward the control board due to a physical stress when the FPC connecters are repeatedly separated from and connected to the control board for replacing the troubled lamp.
The present invention has been made to solve the aforementioned problem, and accordingly it is an object of the present invention to provide a direct lighting type liquid crystal display device having lamp units which can be separated from a bottom chassis without separating FPC connecters from a control board, thereby improving workability for replacing the lamp units and reducing time for replacing the lamp units.
It is another object of the present invention to provide a direct lighting type liquid crystal display device preventing signal lines of the FPC connecters by physical stress.
To achieve the object of the present invention, there is provided the lamp units have a plurality of lamps, each of the lamp including a hot electrode at one end portion of the lamp and a cold electrode formed on the other end portion of the lamp, and lamp holders into which side portions of the lamp where the hot and the cold electrodes are formed are inserted for protecting the lamps. Also, slide slots larger than the lamp holders are formed at a corresponding portion to the lamp, which is selected from one width directional side and the other width directional side of the frame. Closing means for closing the slide slots are formed at the slide slots, respectively. Furthermore, one end portion of each of the flexible printed circuit boards is connected to the source printed circuit board, each of the flexible printed circuit board is bent toward a bottom face of the frame along a portion the frame where the slide slots are not formed, the portion being selected from one width directional side and the other width directional side, and the other end portion of each of the flexibly printed circuit is connected to the control board.
Preferably, lamp supporting members are formed on upper faces of the lamp holders. The lamp supporting members into which the hot portions of the lamp units are inserted enclose three sides of the lamp holders, and necking plates having heights higher than distances between bottoms of the lamp supporting members and portions of the lamp supporting members where the lamp holders are inserted and having widths wider than widths of the lamp holders are formed at sides of the lamp supporting members facing the hot electrodes in order to close the slide slots.